40 individuals, specifically the new generation, over the claims of family tion, specifically to the older generation, and modify drastically the fa that has been so congenial to high fertility. Occupational opportuniti side the family farm would be another blow to the parent-child relati particularly since most such opportunities require migration of the cr allegiances to extra-familial organizations. Such changes would bri; question the pattern of traditional obligations of children to pare place particular strain on the pivotal parental generation, which feel by the traditional demands of their parents without any compensatin on their children. In summary, the new demographic situation of mortality decline a growth may represent a severe structural strain on relationships wi family. From one standpoint this situation may be viewed as a gra\ quence of population growth; from another standpoint it may be rej; a necessary step in transforming the social structure in order to make equilibrium one of low fertility and mortality. The obstacles to sui equilibrium are considerable, because of likely opposition from tho vested interest in the traditional structure—from some heads of gove of armies, of religions, and of families, and from certain of the privi the property-owning. The outcome is obviously problematic, and A in detail from one culture to another, but it seems unlikely that tl social transformation that is sweeping the world can be more than p whatever the current strength of tradition in any particular society. URBANIZATION* Urbanization is a product of a country's history, an irreversib and an inevitable concomitant of economic development. Two years from now it is possible that our century will be recalled as t history when the population of the world was converted from prir to primarily urban. Whereas in 1900 probably no more than a qu; world's population lived in urban settlements, by 2000 it is possi percent or more will be found in cities. Recent Changes in Rural/Urban Population The world figure, of course, does not reveal the great range today. Table 3 provides relevant data on both the level of urbai the tempo of change in the period 1950-70. The developing rej from a low of 10 percent urban (eastern Africa) to 53 perc America and tropical South America). Stated generally, Africa *See Harley L. Browning, "Migrant Selectivity and the Growth of I - • =-- " :„ \r^ n nf this Study.